A known difficulty with the use of inert fluorescent tracers in a system that contains a liquid(s) in contact with solid surfaces, e.g. industrial water systems, is the susceptibility of some of them to degradation of their fluorescent signal upon contact, for a sufficient length of time, with corrosive materials. It would be desirable to have inert fluorescent tracers that are capable of maintaining their fluorescent signal in the presence of common corrosive materials.